The Old Church, founded in the 11th century, but in its present form dating from 1476, contains the monuments of two famous admirals of the 17th century, Martin van Tromp and Piet Hein, as well as the tomb of the naturalist Leeuwenhoek, born at Delft in 1632.
Under the influence of the touchstone of strict inquiry set on foot by the Royal Society, the marvels of witchcraft, sympathetic powders and other relics of medieval superstition disappeared like a mist before the sun, whilst accurate observations and demonstrations of a host of new wonders accumulated, amongst which were numerous contributions to the anatomy of animals, and none perhaps more noteworthy than the observations, made by the aid of microscopes constructed by himself, of Leeuwenhoek, the Dutch naturalist (1683), some of whose instruments were presented by him to the society.
Leeuwenhoek's contributions to the Philosophical Transactions amounted to one hundred and twelve; he also published twenty-six papers in the Memoirs of the Paris Academy of Sciences.
Leeuwenhoek, in 1719, made the remarkable discovery, since abundantly confirmed, that many animalculae, notably tardigrades and rotifers, may be completely desiccated and remain in that condition for long periods without losing the power of awaking to active life when moistened with water.
Antony van Leeuwenhoek appears to be the first to succeed in grinding and polishing lenses of such short focus and perfect figure as to render the simple microscope a better instrument for most purposes than any compound microscope then constructed.